You will be unlikely to miss the connection due to the crowd/queue as they will call people to the front of the queue for flight that are getting close to departure.
I have not experienced this and have missed two flights due to it. I've even asked the staff managing the queue out into terminal whether I can go through because I have a short connection - and the answer is a resounding NO.
Edited to add that I see this all the time during normal domestic check-in, but not at the domestic transfer check-in at SYD intl terminal.